Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case Microbiology B.E Pruitt & Jane J. Stein AN INTRODUCTION EIGHTH EDITION TORTORA FUNKE CASE Chapter 13, part B Viruses, Viroids, and Prions
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Attachment, Penetration, and Uncoating Figure 13.14
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Release of an enveloped virus by budding Figure 13.20
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of DNA Virus Figure Virion attaches to host cell Virion penetrates cell and its DNA is uncoated Early transcription and translation; enzymes are synthesized DNA Late transcription; DNA is replicated 4 Late translation; capsid proteins are synthesized 5 Virions mature 6 Capsid Papovavirus Host cell DNA Cytoplasm Virions are released 7 Capsid proteins mRNA
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Pathways of Multiplication for RNA-Containing Viruses Figure 13.17
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of a Retrovirus Figure Retrovirus penetrates host cell. Virion penetrates cell and its DNA is uncoated The new viral DNA is tranported into the host cell’s nucleus and integrated as a provirus. The provirus may divide indefinitely with the host cell DNA DNA Transcription of the provirus may also occur, producing RNA for new retrovirus genomes and RNA that codes for the retrovirus capsid and envelope proteins. 4 Mature retrovirus leaves host cell, acquiring an envelope as it buds out. 5 Capsid Reverse transcriptase Virus Two identical + stands of RNA DNA of one of the host cell’s chromosomes Provirus Host cell Reverse transcriptase Viral RNA RNA Viral proteins Identical strands of RNA
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Activated oncogenes transform normal cells into cancerous cells. Transformed cells have increased growth, loss of contact inhibition, tumor specific transplant and T antigens. The genetic material of oncogenic viruses becomes integrated into the host cell's DNA. Cancer
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Oncogenic DNA Viruses Adenoviridae Heresviridae Poxviridae Papovaviridae Hepadnaviridae Oncogenic Viruses Oncogenic RNA viruses Retroviridae Viral RNA is transcribed to DNA which can integrate into host DNA HTLV 1 HTLV 2
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Latent Viral Infections Virus remains in asymptomatic host cell for long periods Cold sores, shingles Persistent Viral Infections Disease processes occurs over a long period, generally fatal Subacute sclerosing panencephalitis (measles virus)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Infectious proteins Inherited and transmissible by ingestion, transplant, & surgical instruments Spongiform encephalopathies: Sheep scrapie, Creutzfeldt-Jakob disease, Gerstmann-Sträussler- Scheinker syndrome, fatal familial insomnia, mad cow disease PrP C, normal cellular prion protein, on cell surface PrP Sc, scrapie protein, accumulate in brain cells forming plaques Prions
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Prions Figure PrP c PrP Sc Endosome Lysosome
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Plant Viruses Plant viruses enter through wounds or via insects Viroids Viroids are infectious RNA; potato spindle tuber disease
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Some Plant Viruses Table 13.6
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Virus Families Single-stranded DNA, nonenveloped viruses Parvoviridae Human parvovirus Fifth disease Anemia in immunocompromised patients
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Double-stranded DNA, nonenveloped viruses Mastadenovirus Respiratory infections in humans Tumors in animals
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Double-stranded DNA, nonenveloped viruses Papillomavirus (human wart virus) Polyomavirus Cause tumors, some cause cancer
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Double-stranded DNA, nonenveloped viruses Orthopoxvirus (vaccinia and smallpox viruses) Molluscipoxvirus Smallpox, molluscum contagiosum, cowpox
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Simplexvirus (HHV1 and HHV 2) Varicellavirus (HHV 3) Lymphocryptovirus (HHV 4) Cytomegalovirus (HHV 5) Roseolovirus (HHV 6) HHV 7 Kaposi's sarcoma (HHV 8) Some herpesviruses can remain latent in host cells Double-stranded DNA, nonenveloped viruses
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Double-stranded DNA, nonenveloped viruses Hepadnavirus (Hepatitis B virus) Use reverse transcriptase to produce DNA from mRNA
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, + strand, nonenveloped Enterovirus Enteroviruses include poliovirus and coxsackievirus Rhinovirus Hepatitis A virus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, + strand, nonenveloped Hepatitis E virus Norovirus (Norwalk agent) causes gastroenteritis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, + strand, nonenveloped Alphavirus Alphaviruses are transmitted by arthropods; include EEE, WEE Rubivirus (rubella virus)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, + strand, nonenveloped Arboviruses can replicate in arthropods; include yellow fever, dengue, SLE, and West Nile viruses Hepatitis C virus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, + strand, nonenveloped Coronavirus Upper respiratory infections
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, – strand, one RNA strand Vesiculovirus Lyssavirus (rabies virus) Cause numerous animal diseases
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, – strand, one RNA strand Filovirus Enveloped, helical viruses Ebola and Marburg viruses
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, – strand, one RNA strand Paramyxovirus Morbillivirus Paramyxovirus causes parainfluenza, mumps and Newcastle disease
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-stranded RNA, – strand, one RNA strand Hepatitis D virus Depends on coinfection with Hepadnavirus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Influenzavirus (Influenza viruses A and B) Influenza C virus Envelope spikes can agglutinate RBCs Single-stranded RNA, – strand, multiple RNA strands
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bunyavirus (CE virus) Hantavirus Single-stranded RNA, – strand, multiple RNA strands
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Arenavirus Helical capsids contain RNA- containing granules Lymphocytic choriomeningitis VEE and Lassa Fever Single-stranded RNA, – strand, multiple RNA strands
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lentivirus (HIV) Oncogenic viruses Use reverse transcriptase to produce DNA from viral genome Includes all RNA tumor viruses Single-stranded RNA, two RNA strands, produce DNA
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Double-stranded RNA, nonenveloped Reovirus (Respiratory Enteric Orphan) Rotavirus Mild respiratory infections and gastroenteritis Colorado tick fever